Power transistors commonly employed in automotive and industrial electronics require a low area-specific on-resistance (Ron×A) while securing a high voltage blocking capability. For example, a MOS (“metal oxide semiconductor”) power transistor should be capable, depending upon application requirements, to block drain-to-source voltages Vas of some tens to some hundreds or thousands of volts. MOS power transistors typically conduct very large currents which may be up to some hundreds of amperes at typical gate-source voltages of about 2 to 20 V.
The use of power MOSFETs (“metal oxide semiconductor field effect transistors”) with charge compensation using an isolated field-plate or field-electrode offers an opportunity to reduce the area-specific on-resistance of such a device. This improvement in on-resistance is usually linked to an increased output charge compared to a standard MOSFET device due to the higher doping of the drift region. The output charge may cause a voltage overshoot at fast switching of the device, for example in a synchronous rectification stage of a power supply.
Generally, novel concepts of power MOSFETs which result in improved device characteristics are investigated.
It is an object to provide a semiconductor device in which a trade-off between area-specific on-resistance and switching behavior is improved.